Lecture 2 - How To Examine Cells And Tissues Flashcards

1
Q

What is the definition of a Tissue?
(Short definition)

A

Tissue is a Latin word that means woven

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2
Q

What is the definition of a Tissue?
(Long definition)

A

It is a collection of cells that are adapted to perform a specific function

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3
Q

What are the 4 types of tissue?

A

-Epithelial
-Connective
-Muscle
-Nervous

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4
Q

What is the definition of epithelial tissue?

A

Sheets of contiguous cells, of varied embryonic origins, that cover the external surface of the body and line inertial surfaces including the bodies vessels

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5
Q

Give an example of epithelial tissue

A

The outer layer of the skin
Lining of the small intestine

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6
Q

What does connective tissue consist of?

A

Cells and extracellular proteins/glycoproteins and gels

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7
Q

What are the main cells found in connective tissues?

A

Fibroblasts
Chondrocytes
Osteoblasts/osteocytes/osteoclasts
Stem cells/progenitor cells

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8
Q

What are the main products of connective tissues?

A

Fibres
Ground substance

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9
Q

What does ground substance consist of?

A

Cells
Extracellular matric

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10
Q

What are the 3 types of muscle tissue?

A

Skeletal
Cardiac
Smooth

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11
Q

What is the function of nerve tissue?

A

Fast communication system of the body

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12
Q

What is the relationship between millimetres and micrometers?

A

There are a 1000 micrometers in 1mm

Or a millimetre is x1000 larger than a micrometer

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13
Q

What is the relationship between micrometers and nanometers?

A

There are 1000 nanometers in a micrometer

Or a micrometer is x1000 times larger than a nanometer

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14
Q

What is the relationship between millimetres and nanometers?

A

There are 1000000 nanometers in 1mm

OR a millimetre is x1000000 larger than a nanometer

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15
Q

What is the definition for the Limit of Resolution?

A

The smallest distance by which 2 objects can be separated and still be clearly distinguishable as 2 separate objects

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16
Q

Which has better resolving power, light microscopes or electron microscopes?

A

Electron microscopes

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17
Q

What methods are there to obtain a tissue biopsy?

A

Surgery and then dissection
Scraping methods (curettes, scalpel scrapes)
Sharp needles (needle biopsy, pipelle)
Venupuncture (for blood smears)

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18
Q

What methods of tissue biopsy can be used to obtain an endometrial sample?

A

Scraping (endometrial curettage)
Sharp needle (Pipelle)
Surgery (hysterectomy)

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19
Q

What method can be used to obtain a bone marrow biopsy?

A

Sharp needle

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20
Q

Why does a specimen/biopsy require fixing/fixation?

A

To prevent digestion by microbes or being destroyed by decay

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21
Q

What does fixation remove from a specimen?

A

Water
Stiffens biopsy

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22
Q

What is the most common fixative that is used in preparing biopsies?

A

Buffered formalin solution

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23
Q

How can fixation cause biopsy shrinkage and formation of artefacts?

A

If a specimen is left in fixative for too long it becomes to dehydrated shrinking

24
Q

Once a biopsy has been obtained and fixated, what is the next step?

A

Embedding

25
Q

What happens in embedding?

A

Dehydration of specimen in different concs of alcohol

Then its immersed in hot paraffin wax which is allowed to solidify

26
Q

What is the normal medium of choice for embedding?

A

Paraffin wax

27
Q

What happens after embedding has occured?

A

Sectioning

Thinly sliced by microtome

28
Q

What is usually done after a specimen has been sectioned/thinly sliced?

A

Staining

29
Q

Give some examples of stains commonly used:

A

Haemotoxyin and Eosin (H&E)
Massons trichrome
Periodic Acid-Shiff stain

30
Q

What does the Haematoxylin stain part of H&E stain and what to colour does it stain?

A

Stains nucleus BLUE most strongly

31
Q

What does the Eosin component of H&E stain and what colour does it stain?

A

Stains alkali stuff (the proteins)
Cytoplasm and extracellular matrix stained PINK the most strongly

32
Q

Why is H&E (haematoxylin and Eosin) useful?

A

Nuclei are clearer and more detailed cytoplasm

33
Q

What is Periodic Acid-Shiff stain commonly used to stain and why?

A

Kidney
Stains anything with sugar attached pink
Lots of sugar in kidney

34
Q

What is immunohistochemistry/immunostaining?

A

Using labelled antibodies which bind to specific tissues/cells so they can be easily examined

35
Q

How does immunohistochemistry allow us to see specific cells or tissues?

A

A primary antibody that is specific to the antigen found on the specific cell/tissue we want to view binds to the cell of interest

A secondary labelled antibody is bound to the primary antibody. This antibody has a coloured dye bound to it which shows the presence of the specific antigen/cell

36
Q

How does immunofluroescence work?

A

Labelled primary antibody with fluroscent tag attached binds to specific antigen on cell of interest

Signal is emitted onto the fluorescent tag, it fluoresces and is visible

37
Q

What is the advantage of Staining specimens?

A

It creates clear contrast so a specimen can be viewed in detail

38
Q

What is a frozen section?

A

Surgical specimen on metal disc rapidly frozen
Cut with microtome in a freezer
Stained with H&E

39
Q

What is the advantages of a frozen section over a Paraffin wax formalin fixed specimen?

A

Prepared rapidly (used during surgeries)
Can be done to fresh tissues

40
Q

What are the disadvantages of a frozen section?

A

Poor stain retention
Do not last very long (months)
Poor clarity

41
Q

What are the advantages of a Paraffin wax formalin fixed specimen over a frozen section?

A

Last forever
Clear under microscope
Used for diagnosis

42
Q

How are tissues prepared for electron microscopy?

A

Fixed with Glutaraldehyde
Embed in Epoxy resin
Stain osmium tetroxide

42
Q

How are tissues prepared for electron microscopy?

A

Fixed with Glutaraldehyde
Embed in Epoxy resin
Stain osmium tetroxide

43
Q

What are the differences between light a electron microscopy?

A

L = normal colours E = monochrome
L = cheap easy prep E = Expensive difficult
L = living and moving specimens E = Dead and inert
L = lower mag and res E = Higher mag and res

44
Q

What does resolution of a microscope depend on?

A

The wavelength of the radiation it uses

45
Q

Why do electron microscopes have a better/smaller limit of resolution than light microscopes?

A

They use electrons which have a smaller wavelength than light

46
Q

What are the 2 types of electron microscopy?

A

TEM (Transition Electron Microscopy)
SEM (Scanning Electron Microscopy)

47
Q

What is SEM good for?

A

Viewing 3D images of the surfaces of specimens

48
Q

What is TEM good for?

A

Viewing 2D images of Intracellular organelles

49
Q

What is confocal microscopy?

A

A laser excites a fluorescent dye in specimen
Light emitted passes through pinhole to detector

50
Q

What are the advantages of confocal microscopy?

A

Entire depth of tissue can be examined
3D images can be created

Can evaluate and lead to rapid diagnoses of eye diseases

51
Q

What is the advantage of Phase contrast microscopy?

A

Living cells can be viewed in their natural stated since fixing and embedding is not required

52
Q

What is dark field microscopy?

A

Illuminating a live sample with light that isn’t collected by the objects lens. This makes the black background with bright objects on it

53
Q

What are the advantages of Dark field microscopy?

A

Creates an extremely clear contrast
Easy to do

54
Q

What stain is best to detect sugars/polysaccharides ?

A

Periodic acid-schiff reagent

55
Q

What is the simple order of preparing a tissue sample for H&E staining?

A

Fixation
Embedding
Cutting/microtomy
Staining
Mounting

56
Q

What type of histiological technique is likely to be used to identify presence or absence of a tumour?

A

Haematoxylin and Eosin Staining (H&E)